1. Technical Field
Disclosed is a low toxicity solvent system used for the manufacture and use of polyamideimide and polyamic acid resin. The inventive solvent system can be used for either the manufacture polyamideimide resins or the dissolution of polyamideimide resins for use in coating solution applications.
2. Background Art
Polyamideimide and polyamide amic acid resin polymers (hereinafter referred to as PAI) are well-known thermally stable polymers that are used for many high performance coating applications due to their excellent adhesion, temperature resistance, and high strength. The primary route to synthesizing polyamideimide polymers in a form that is convenient for the manufacture of coatings is by reacting diisocyanate, often 4,4′-methylene diphenyldiisocyanate (MDI) with trimellitic anhydride (TMA). In this process, PAI polymers are typically manufactured in polar aprotic solvents such as N-methyl amide compounds including dimethylformamide, dimethylacetamide, N-methylpyrrolidone (NMP), N-ethylpyrrolidone. See for example U.S. Pat. No. 2,421,021, U.S. Pat. No. 3,260,691, U.S. Pat. No. 3,471,444, U.S. Pat. No. 3,518,230, U.S. Pat. No. 3,817,926, and U.S. Pat. No. 3,847,878.